Games that don't require a board, cards, or a table
Here are a list of well-known but entertaining games that don't require a board, cards, or a table, only the use of one's brain and voice.
Twenty Questions
One player (the answerer) thinks of an object. Everyone else asks the answerer yes or no questions about the nature of the object (e.g. is it edible?). The answerer must answer truthfully. The goal of the guessers is to reach the correct answer in as few questions as possible, with a traditional cutoff for victory at an eponymous twenty questions. It's sometimes useful to restrict the set of legal objects to a certain category. Otherwise, if playing competitively abstract concepts like arrogance or historical events like the Battle of Antietam can be prohibitively difficult to guess.
French Toast
One player (the answerer) will think of an object, and everyone else is a guesser. There is a notion of the “current closest guess” X, which begins as “french toast.” The guessers take terms, and will make guesses in the forms of stating an object Y. The answerer will think of whether X or Y is semantically closer to their object, using whatever criteria they deem reasonable, and respond with the one that’s closer, replacing X with the closer guess. The goal of the guessers is to guess the object. Following is an example of the beginning of a game. Player A is the answered and Player B is a guesser.
(A's word is a calculator)
B: School?
A: School (you often use a calculator at school)
B: Teacher?
A: School (A thinks teachers are less likely to use calculators than other people at a school)
B: English class?
A: School (English class is a class where you're particularly unlikely to use a calculator)
B: Math class?
A: Math class! (B is getting pretty close)
B: Geometry?
A: Math class (A thinks geometry is one of the branches of mathematics least associated with calculators)
Concentration
Someone picks a category, and then everyone takes turns naming things that fit in the category. Whoever cannot think of an example or repeats something that someone has already named is eliminated. Play until only one person remains. Optionally, include a time limit. I originally learned this game as a child as Concentration 64, with accompanying claps and lyrics, but these days I play without.
Word Chain
Everyone takes turns saying a word that has a starting letter which matches the ending letter of the previous word (e.g. apple → elephant → torus). Whoever cannot think of a word or repeats a word is eliminated. I’ve played this with the entire dictionary on a particularly long drive, but to keep playing time reasonable, it’s probably best to restrict words to a single category like food items. A common variant is to play this with the names of famous people, matching starting letters of last names with the starting letter of the first name (e.g. Taylor Swift → Sanna Marin → Michael Dukakis).
Contact
Requires at least three players. One player (the defender) comes up with a target word e.g. "coral" and tells everyone the first letter. The other players work together to guess the word.
A guess is initiated by one guesser giving a hint for a candidate word that they think could be the target word e.g. "another name for tubercolosis" intending for the candidate word to be "consumption." If another guesser thinks they the word the first guesser is referring to, they may say "Contact." At this point, the defender may attempt to determine what the candidate word is. If the defender guesses correctly, then that candidate word cannot be used and the guessers must come up with another candidate word. The defender is not allowed to say their own target word. If the defender cannot figure out what the candidate word is (with some reasonable time limit), then the two guessers (the clue giver and the one that said contact) count off for three and say the candidate word at the same time. If they match, the contact is successful and the defender must reveal the next letter in their wrod. If they do not match, the contact fails, and the guesser
The game ends when the defenders successfully perform a contact for the target word (or if the defender accidentally says their own target word), in which the guessers win, or when the defenders fail to make a contact for the target word (one person in the contact said the target word but the other did not) or give up, in which case the defender wins. Following is an example of the beginning of a game, where Player A is the defender and Player B and C are guessers.
A: I've got a word that starts with C.
B: Another word for tubercolosis?
C: I think I know what you mean. Contact.
A: No idea. Go ahead.
B and C: 3, 2, 1, consumption.
A: The second letter is O.
C: A place where you can buy hot dogs?
A: Costco?
C: You got me. How about an island of France?
B: Contact.
A: Constantinople? No, I have no clue.
B and C: 3, 2, 1, Corsica.
A: The third letter is R.
This is probably my favorite game of the bunch, though it is a bit difficult to explain; probably best to demonstrate with a few examples when teaching this game to a new group.